This invention relates to vibration-damping materials, and in particular to vibration-damping laminates having constraining layers.
A structure that is under the influence of internal and/or external forces, such as an automobile panel, tends to vibrate and produce undesirable noise. It is known to reduce the vibration of the structure by attaching a vibration-damping material to the structure. The vibration-damping material often consists of a single layer of a viscoelastic material, such as asphalt or rubber. It has been found particularly useful, however, to use a laminate as the vibration-damping material, wherein the laminate includes a viscoelastic layer and a constraining layer with a high Young's modulus. Such a constraining layer increases the damping effect of the laminate, and supports and protects the viscoelastic layer and the structure. Conventionally, the constraining layer is composed of metal because metal has a high Young's modulus.
Although a laminate with a metal constraining layer provides numerous advantages, such a laminate also has disadvantages. A laminate with a metal constraining layer has increased weight, is harder to shape, is more expensive to produce, and is usually more expensive to install.
Based upon the foregoing, there is a need in the art for an improved vibration-damping laminate. The present invention is directed to such a laminate.